Arc tube support



April 8, 1958 F. JENNE, JR, ET AL 2,830,210

ARC TUBE SUPPORT Filed Sept. 16. 1954 Fig.1.

Inven tovs: Fvank Jennadwi, Robev t W. Schmies,

bg-Wwg/ I Their A t hovneg.

- 2,830,210 ARC TUBE SUPPORT Application September 16, 1954, Serial No. 456,503

3 Claims. (Cl. 31325) The present invention relates to high-pressure electric discharge lamps having an inner arc tube of vitreous material, an outer vitreous envelope and a mount structure supporting said tube in said envelope.

The principal objects of the present invention are to provide a support member for the are tube in lamps of the above type which is adapted for universal use with either a cylindrical type of seal or a flat press type of seal; has a configuration such as to obstruct a minimum of light from the arc tube, and is economical to manufacture and assemble.

Further objects and advantages of the invention will appear from the following detailed description of a species thereof and from theappended claims.

In accordance with the objects of the invention, the support member embodying the present invention is in the form of a clamp and preferably consists of an elongated doubled strip of stiffiy resilient metal having a seal grasping, expanded center portion square in cross section with one of the diagonals of the square-shaped portion extending longitudinally of the strip and the other of said diag- 1 onals extending normal to the strip. The doubled strip, before being permanently mounted in the lamp, is in the form of a clamp with the free ends of its jaws spaced apart to facilitate mounting the support member around the seal in the assembly of the lamp. Preferably, when used with seals of the fiat press type, the edges of the seal are engaged by the corners at the ends of the diagonal normal to the strip. When used with the seals of the cylindrical type, the sides of the square-shaped, seal engaging center portion of the doubled strip grasp between them the cylindrical wall of the seal. The use of a single type of support in place of the two types used heretofore efiects substantial savings in themanufacture of the lamps.

In the drawing accompanying and forming part of this specification, an embodiment of the invention is shown in which:

Fig. 1 is a front elevational view of a discharge lamp of the high-pressure type in which the support members for the inner are tube embody the present invention; I

Fig. 2 is a top plan view on an enlarged scale of the mount structure of the lamp shown in Fig.1;

Fig. 3 is a similar view of a mount structure showing a cylindrical type of seal grasped by the support member of the present invention; and

Fig. 4 is a perspective view on a more enlarged scale, as seen from above, of the support member of the present invention. I Referring to Fig. 1 of the drawing, the lamp illustrated is of a well-known commercial type except for the arc tube supports described in detail hereinafter and, therefore, a brief description of the lamp will suflice for the purpose of providing a complete understanding of the invention.

The lamp comprises an outer vitreous envelope I having a re-entrant stem 2 through the pinched or pressed niteci Sttes ate 2,839,219 Patented Apr. 8, 1958 are connected at their outer ends to the contacts of the usual screw-type base 6 of the lamp and terminate within the outer envelope 1 for connection to the terminals of the inner arc tube 7. The inner arc tube is made of hard vitreous material, such as quartz, and has sealed therein at opposite ends thereof a pair of main discharge supporting electrodes 8 and 9 of tungsten and material of higher electron emissivity, such as alkaline-earth oxide, thorium and mixtures thereof. The inleads 10 and 11 of the electrodes 8 and 9 constitute the terminals of the arc tube.

An auxiliary starting electrode 12 of fine tungsten wire is sealed into one end of the arc tube 7 adjacent the main electrode 9. The current inlead wires for the said electrodes 8, 9 and 12 have a foliated portion of molybdenum hermetically united by fusion with the quartz of the pinched tube end portions constituting the flat pressed seals 14 and 15 extending outwardly from the arc tube, as described and claimed in the Noel and Dell Patent 2,667,595, patented January 26, 1954, titled Ribbon Lead Construction, and assigned to the assignee of this application.

In the 400-watt size. the arc tube 7 has a filling of a 7 starting gas, such as argon, at a pressure of about 2 centimeters at room temperature and a measured quantity of mercury sufficient to produce a high-pressure, unsaturated vapor atmosphere at the operating temperature of the arc tube. The outer envelope 1 is filled with nitrogen at about one-half atmosphere pressure.

The mount for the arc tube 7 within the outer envelope 1 comprises a harness made up of a U-shaped stifi' nickel iron alloy wire having its center portion 16 welded to the inlead 4 sealed into the stem 2 and its parallel legs 17 and 18 extending longitudinally of the arc tube 7 and terminating at the opposite end of the outer envelope 1. A pair of spring members 19 and 19' are welded to the legs 17 and 18, respectively, of the U-shaped harness member and within the neck 20 of the outer envelope 1. The springs 19 and 19 press against the wall of the neck 20 to provide additional support for the arc tube 7.

The outer envelope 1 has a paraboloidal-shaped portion 21 having a reflecting internal coating 22 of silver thereon and a light transmitting dish-shaped end 23 which is usupart 3 of which extend two leading-in wires 4 and 5 which ally lightly frosted to provide light diffusion. The are tube 7 is supported by the mount in the longitudinal axis of the paraboloidal portion 21 of the envelope 1.

A spring member 24 is welded to the upper end of the leg 17 of the harness and, while normally spaced from the envelope 1, the member 24 serves as a bumper to prevent the upper end of the mount or the arc tube striking and possibly breaking the wall of the outer envelope 1 when the lamp is subjected to severe physical shocks during shipment.

A centrally perforated reflecting metal disc 25 is welded to the legs 17 and 18 of the harness and is located Within the neck 19 to protect the stem 2 of the envelope 1 from excessive temperatures during operation of the lamp and acts as a neck bumper to prevent excessive movement of the mount during shipment. The flexible stranded metal wire leads 26 and 27 of the main electrode 9 and, the starting electrode 12, respectively, extend through the perforation in the disc 25 and are electrically insulated therefrom and from each other by the glass tubes 28 and 29, respectively.

The electrical connections of the lamp are conventional. The flexible stranded metal wire lead 26 of the electrode 9 is welded to the inlead 5 sealed into the stem 2 the flexible stranded metal Wire lead 39 of the electrode 8 is Welded to the inlead 1t] and the leg 18 of the harness, the curved portion 16 of which is welded to the inlead-4 sealed into the'press 2, and the flexible stranded metal wire lead 27 of the auxiliary electrode 12 is connected to the leg 18 of the harness through the resistance member 31 welded to the said leg 18. V

In the400 watt size, the quartz arc tube 7' of' the lamp is about inches in overall length including the fiat seals 14 and 15, andabout 78 inch in diameter with a wall thickness of approximately 1 millimeter. The inner ends or tips of the arc discharge supporting main electrodes 8 and 9 are separated within the arc tube a distance of about 70 millimeters from each other.

The seals 14 and 15 at the ends of'the arc tube 7 are each about /2 inch Wide and about /2 inch long. The width of the said seals varies slightly from lamp to lamp due to the inherent difficulties of working quartz'to exact dimensions. 1

In accordance with the present invention the arc tub 7 is attached to themount within the envelope 1 by a pair of transverse metal clamp-shaped support members 32 and 33 welded to and bridging the legs 17 and 18 of the U-shaped harness and grasping the flat press seals 14 and 15 attheir side edges as shown in Figs. 1 and 2.

The supports 32 and 33 are identical in structure and are mounted in the lamp in. the same'rnanner. The following description of the structure of the support 32 and the manner in which it is made and incorporated in the lamp structure will therefore constitute a disclosure of these features of the support 33.

The support 32 is in the form of a clamp constituted preferably by an elongated single strip of stifily resilient metal folded double and with the jaws of the clamp formed by the folds of the strip suitably bent so as to provide at the center of the support a square-shaped grip 34 for receiving and grasping an external seal of the arc tube 7. l

The form of the support before it is attached to the legs 17 and 18 of the mount in the manufacture of the lamp is shown in Pig. 4 of the drawing and the form thereof after it has been attached to the aforesaid legs 17 and 18 is shown in Fig. 2.

The support 32 is cut from a strip of metal, such as chrome-iron or nickel-plated iron, and shaped in a die which forms therein the right angle bends constituting the corners 35 and36 of the square grip 34. In the same operation the die crimps the strip along a transverse line at its center as shown at 37 in the drawing. The strip is then folded along the crimped line 37 into the form of a clamp shown in Pig. 4 with the ends 38 and 39 of the strip spaced apart for convenience in assembling the lamp.

In assembling the arc tube on the lamp mount, the

support 32 is so positioned around the seal 14 that the corners 35 and 36 thereof engage the side edges of the seal with the ends 38 and 39 of the strip support in contact with each other. After the support has been so positioned around the seal, it is welded to the legs 17 and 13 of the harness in the position shown in Fig. l of the drawing. The ends 33 and 39 of the strip are welded together in this operation. The welds are made near the extremities of the support 32 and the seal 14 is slightly wider than the length of the diagonal between the centers 35 and 36, so that the folds of the doubled strip support between the grip 34 thereof and the'welded parts thereof are flexed slightly outward from each other and the support thusexerts a firm but yielding grip on the seal.

The support 33 is attached to the mount in the same manner, and this may be done before or after or at the same time that the support 32 is attached thereto.

As mentioned above, the support embodying the invention is also useful in connection with lamps having arc tubes provided with seals of cylindrical shape.

In Fig. 3 of the drawing, the support 32 is illustrated in conjunction with a seal 40 of cylindrical shape provided with an inlead 41. -As shown in this figure, the sides of the square-shaped grip 34 of the support engage the cylindrical wall of the seal and the support exerts a similar gripping action on the cylindrical seal 40 as it does on the flat seal 14 illustrated in Fig. 2. Arc tubes with cylindrically shaped seals are well-known in the art and are useful in lamps of the type illustrated in Fig. l of the drawing, the arc tubesper se having substantially the same structure as the arc tube 7 illustrated'in Fig. l, with the exception of the cylindrically shaped seals at the ends of the tube.

While we have shown and described the preferred embodiment of the invention, it will .be understood that we contemplate that changes in the structure of the clamp support may be made without departure from the spirit of the invention; for example, the support may be made of two elongated strips of metal, each shaped, assembled and fastened to the harness as one of the jaws of theclamp support shown and described above, and the support, whether constituted of a single folded memher or two properly shaped members, may consist of wire.

What we claim is new and desire to secure by Letters Patent of the United States is: a

1. Abigh-pressureelectric discharge lamp comprising, an outer vitreous envelope, a vitreous arc tube having externally extending seals at its ends, and a mount supporting said tube in said envelope, said mount comprising a pair of spaced parallel stiff metal wires and means securing said tube to said wires, said means consisting of a pair of elongated clamp supports each constituted by stiffly resilient metal and having bent jaws providing at the center of the support a square-shaped grip for an external seal of the arc tube, said supports beingattached to and bridging said wires with their square-shaped grips grasping said are tube seals and supporting said arc tube between said wires and within said envelope, the seal gripping parts of each of said supports being spaced an appreciable distance from the extremities of the supports attached to said wires and the resilient jaws of said supports being flexed slightly outwardly from each other by the gripped seal whereby said supports exert a firm but yielding grip on said seals.

2. A high-pressure electric discharge lamp comprising, an outer vitreous envelope,- a quartz arc tube having externally extending seals at its ends and a mount supporting said tube in said envelope, said mount comprising a pair of spaced parallel stiffmetal Wires and means securing said tube to said wires, said means consisting of a pair of elongated clamp supports each constituted by an elongated doubled thin strip of stifily resilient metal and each having bent jaws providing at the center of the support a square-shaped grip for an external seal 'of the arc tube, said supports being attached to and bridging said wires with their fiat sides against said wires and their squareshaped grips grasping said are tube seals and supporting aid arc tube between said wires and Within said envelope, the seal gripping parts of each of saidsupports being spaced an appreciable distance from the extremities of the supports attached to said wires and the resilient jaws of said clamp supports being flexed slightly outwardly from each other by the gripped seal whereby said supports exert a firm but yielding grip on said seals.

3. A high-pressure electric discharge lamp comprising, an outer vitreous envelope, a quartz arc tube having externally extending seals at its endsand a mount supporting said tube in said envelope, said mount comprising a pair of spaced parallel stiff metal wires and means securing said tube to said wires, said means consisting of a pair of elongated clamp supports each constituted by an elongated doubled thin strip of stiffly resilient metal and each 5 said supports being spaced an appreciable distance from the extremities of the supports attached to said wires and the jaws of said supports being flexed slightly outwardly from each other by the gripped seal whereby said supports exert a firm but yielding grip on said seals.

References Cited in the file of this patent UNITED STATES PATENTS 1,935,685 White Nov. 21, 1933 6 Cox Ian. 19, 1937 Germer Jan. 23, 1940 Garreau Sept. 9, 1952 Noel Sept. 23, 1952 St. Louis et a1 Mar. 2, 1954 

